Brand new research shows that the size, activity and connectivity in parts of the brain associated with reward and addiction decrease the more frequently someone watches porn. While there is over-hype and misleading interpretations of the data in the media, these changes are in support of recent claims that high porn consumption is associated with inhibition of sexual gratification, porn addiction and alteration of sexual behavior and intentions.

It’s natural to like pornography

Despite universal porn consumption that goes beyond demographic pigeonholing, in actuality, we know surprisingly very little about the long-term effects that pornographic content has on our biology, psychology, family and community life, and well-being.

The short-term effects of sexual arousal on the other hand, porn or no porn, are a little better understood and were recently reviewed in another article on this site. In short, in order to be turned on by something, there are four combinatory components in action: cognitive, emotional, physiological and motivational, all of which are ruled by four different, yet interconnected, systems in the brain.

Common sense logic and perpetuation of the species dictates that it is only natural to enjoy sexually explicit material. Recent research even demonstrated that male macaque monkeys would much rather look at the bottoms of the opposite sex than get a tasty treat. Put simply, sex sells!

Is pornography addictive?

When looking more closely at the brain and behavior in us humans however, watching porn bears resemblance with reward and novelty-seeking behavior, and as such, popular science literature has long suggested that high frequencies of porn consumption would dampen the brain’s reward and motivation networks neural response to sexual stimuli through over-stimulation.

This dampening, as with drug addiction, would promote compulsive, porn addiction behaviours and changes in normal sexual intent and motivation. Due to the cross-talk with the cognitive, emotional and physiological components of sexual arousal, this would ultimately influence all aspects of sexual arousal, and lead to sexual dysfunction.

While many studies have hinted at the potential dangers of watching porn and porn addiction, a 2013 EEG study (among others) supported porn advocates views that the brains of porn addicts and non-addicts are not that different, and that porn addiction was simply associated with high libido or with the use of pornographic images to cope with negative emotional states or life dissatisfaction. The EEG study was highly contested in the media, but nonetheless, it further fueled the confusion of the masses in understanding the script when it comes to watching porn.

Due to a lack of evidence that watching porn is associated with changes to the brain, pornography addiction was not included in the recently revised Diagnostic and Statistical Manual of Mental Disorders (DSM-V). Self-proclaimed porn addicts may tend to disagree, with many stating that their interest in porn may have started as such, but this initial interest lead them towards compulsive, uncontrollable porn-seeking behavior.

The latest take on porn in the brain

Thankfully, a recent study using fMRI sheds light on this confusing and contradictory picture of porn. By using fMRI, researchers were able to look beyond cortical brain activity and found that the differences lie deeper than the cortical EEG recordings could detect, in the more evolutionary ancient and subcortical reward system structure called the striatum.

In the study, 64 healthy adult males with a broad range of pornography consumption (from 0-19.5 hours per week), had fMRI scans when viewing 60 sexual images from porn sites and 60 non-sexual images. The researchers were looking for correlations between the number of hours per week, as well as the lifetime period that they had been regularly watching (or not watching) porn, and associated differences in brain structure and function.

They confirmed that the more porn an individual watches the more they used legal and addictive drugs like alcohol and the more depressed the individual felt. More significantly, they also noted differences in the brain: A decrease in activity of the left striatum (in the putamen) and a decrease in grey matter volume of the right striatum (in the caudate), although these effects where not completely laterelized, and the right striatum’s reduction in connectivity with the left dorsolateral prefrontal cortex (DLPFC). These results remained even when controlling for internet and sex addiction.

The reduction in activity in the putamen in response to sexual stimuli and reduced size of the caudate, for those watching more porn, correlates well with a down-regulation of motivational circuitry inhibiting the natural response to sexual stimuli. The natural response being the promotion of sexual motivation and excitation. This corresponds well with reports that excessive porn use leads to a lack of excitation and motivation with one’s real life sexual partners.

Perhaps more significant is the reduced size of the caudate and its connectivity with the DLPFC. The striatum is intimately associated with the neuroplastic shift in having your actions guided by higher cognitive processes (the action-outcome system), to bypassing the need for complex thought in habit formation (the stimulus-response system). The action-outcome system involves activity of the DLPFC, which is associated with goals, intentions and future planning in the direction of one’s actions in response to a given stimulus.

It’s not surprising that malfunction of the DLPFC is associated with socially inappropriate behaviors in various mental disabilities and in drug-seeking and addictive behavior. What could be happening with increased porn consumption is that the more one watches porn the less connected the sexually activated part of the caudate is with the DLPFC. Thus, seeing a certain level and type of pornographic sexual activity and behavior becomes the norm and so there is a disruption in the thought processes and evaluation of the potential negative outcomes of turning to porn, coupled with more compulsive, habitual behavior driving the individual towards their next X-rated fix.

What does this mean for our future relationship with porn?

Further expansion of this work is required to tell whether regularly watching porn actually caused the observed differences or that inherent differences already existing in the brain predisposes an individual to a certain level of porn consumption – it’s a chicken or the egg dilemma.

However, with what we know about the brain and particularly the striatum and plasticity, it should not surprise us to find that repetitive porn use will cause neuroplastic changes, irrespective of inherent structural and/or functional differences. With the malleable, highly neuroplastic brains of teenagers making them fast habit learners (they just pick things up quicker), coupled with the rise of internet porn, this is where alarm bells should and are resoundingly ringing.

Officially sorting out this chicken or the egg dilemma could pave the way for the whole world to step up to the plate and do the utmost to protect our children’s brains. The UK’s Department for Culture, Media and Sport has been one of the first to take the helm and steer children away from pornographic websites.

New laws are being drawn up that will force adults to prove their age with credit card details or other documents before they can access porn sites or purchase adult content. However, this is only for British websites, whose slice of the global porn pie is a marginal 1-2% at best. Without worldwide cooperation, little can be done to prevent kids from the slippery dopamine greased slope to over-consumption of porn and potential porn addiction.

And even with these measures in place what is protecting us adults, and more importantly, do we really need protection in the first place? Are there negative outcomes related to the moderate pornography consumption of a casual porn user that outweigh any putative benefits? Hopefully, maturation of research on pornography will promote biopsychosocial-based education and will answer key questions such as:

What are the differences in frequent exposure to different pornography formats?

How does watching hard-core porno flicks differ from the extremely rare ‘ethical’ porn, where porn is sex-positive, depicts sexual consent and agency, and prioritizes female pleasure?

How much porn is too much porn and what constitutes a porn addict?

Are there benefits of watching porn and if so, could pornographic material be used strategically for treating sexual dysfunction as opposed to inducing it?

Expanding on current scientific research will hopefully paint a pornographic picture of the healthiest use of erotic material in our society. As yet, to be honest, we haven’t got a clue!

Carla Clark, PhD, is BrainBlogger's Lead Editor and Psychology and Psychiatry Section Editor. A scientific consultant, writer, and researcher in a variety of fields including psychology and neuropsychology, as well as biotechnology, molecular biology, and biophysical chemistry, you can follow her on Facebook or Twitter @GeekReports

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